Exactly!
Yes, that cvars will do the same than the Reset one, but after X frames. But the huge blinking due to GI resets will be very noticeables too.
I finally preferred the Reset one over that one, because you can execute it only when you relly needed it (for example, after being completely in night, just after sunset).
Thanks for your support and answer, the problem is that in this scene neither GI Raytracing + Shadows Raytracing work!
I tried the combination in an Epic free interior appartment model and everything works fine, so I can’t figure out the problem…
GI Raytracing and Raytraced shadows got replaced with lumen and VSM. Generally you shouldn’t be using them as they are depreciated and not as well supported as lumen or vsm.
Ray traced shadows aren’t deprecated, they’re not flagged as such in the docs or the engine and received updates in both 5.2 and 5.3.
agreed. they are very much supported. and they are further improved in 5.4 and 5.5. the vsm alternative for low video memory specs, given the gpu can hande all the rays. they are maybe not the right choice when you spam overlapping nanite instances but in a well designed game world they are totally usable. hmm
I thought they were missing some features and had more artifacts, glad it’s still getting improved on.
RTGI definitely got deprecated bc it was quite bad, RT reflections as well I think bc lumen can do everything they did and better (including working with static lighting). RTAO still exists, but I believe that’s because RTAO is nonphysical and not part of a coherent lighting system like lumen.
Yeah RT reflections have a lot of skylight leaking if you try to use it.
Yes and is correct.
But how can we get some good quality reflections and refraction? Raytracing seems still better. In any case, still didn’t find the solution to my problem yet.
i think true raytraced refraction is a lil durther down the line. i can bounce that code thru my mind’s eye. raytracing thru translucent surfaces and correctly blending their colors over the next bounce is not that easy. it’s a “reverse” blend. a ray payload that gotta be carried thru for every translucent refraction bounce and a ton of math at the end. the color accumulation per bounce is the issue. it’s not very efficient.
imo… lumen reflections are as good they can be for now, while still maintaining interactive framerates on a broad spectrum of hardware. so… ima say… deal with it. shrugs
Ok and good to know, but whatever quality number I use they’re always too blurred!
On the sphere’s reflection you can also see that the reflected shadows are too precise and there is no “area shadows” effect.
you sure you use full 0 roughness on that ball? also… i noticed that you use post chromatism. how much does that do to the reflection? i don’t wanna build a test rn.
my test reflections are clean af. ofc temporal in motion. i don’t mind that. no aggressive post volumes either.
screenshot is a out of the box 5.5 daily, btw. build it 3 hours ago. looks good. my highrise map got some nice fps now. not stable but doesn’t dip below 40 anymore at 100% 1080. i mean… i’m totally rt limited in that one, anyway. my gpu runs it without sweating. 
had to notice the sun size broke in my map. a lil test was in order. directionality. source angle or soft angle?
the soft angle does some overcast looking reflections but hard shadows.
using both does overcast shadows, but the reflection is lost. or… added on top.
i’d guess a kinda fusion would be nice looking for this sun. it’s to late for me to start coding, tho. hmm
They trimmed the lumen RT payload size to something like a third of what it was in UE4. I’m honestly pretty impressed that they got refraction working well at all given that constraint. I wonder if substrate will result in some sort of payload rearchitecting to avoid all the cost.
Thanks and I’ll check that!
As for the post chromatism, I dont’think it can change the blurry feeling on the reflections too much, but I need to check this too.
Not tested, but probably Lumen reflections are only reflecting hard shadows. RT reflections could reflect hard shadows and area shadows, if selected. Not sure if Lumen is compatible or if it has the same switch, to select the kind of reflected shadows.
Have you tried disabling temporal accumulation, as commented before?
Hey! It is a great expierence to use it.
Lumen reflections have had a performance increase in 5.4 by 1ms in a test scenario at 1440p on a desktop 3060!
I’m talking legit 1ms, not .2 under or over. That 1ms is pretty awesome, but TSR also become more expensive by 1ms(again no .2 under or over) which canceled out any performance gain Lumen got but I don’t even like TSR so it’s not a problem for me.
Btw, this is the first time UE5.4 compiled so I’ll update this post regarding anymore issues(hoping to see Lumen remains stable in motion without TAA etc)
EDIT: Feedback:
A Cvar that would really help things out would to limit reconstruction from Bilateral and Reconstruction samples from affecting lower roughness like 0.0, 0.01. Reconstruction is needed and more beneficial at 0.05-0.4. When close to 0.0 or 0.01, ruin what temporal accumulation already does a good job for.
Lumen Reflections do not jitter in a way where 0.0 reflections can be constructed to the main internal resolution as frames pass on low roughness, if they were, we could get high res reflections in around 5 frames. I guess this was unfortunately handed off to TSR.
To see what I mean, Mirror reflections with (r.Lumen.Reflections.DownsampleFactor 2 + r.Lumen.Reflections.ScreenSpaceReconstruction 0) looks the same as: (r.Lumen.Reflections.DownsampleFactor 1 +r.Lumen.Reflections.ScreenSpaceReconstruction 1)
r.Lumen.Reflections.Temporal.MaxRayDirections 32 is really great at 1/4 res reflections the only thing missing is standalone temporal reconstruction on 0.0-0.05.
5.3 r.Lumen.Reflections.ScreenSpaceReconstruction 0 takes off 5.55555556 of reflection cost vs 22.3214286% in 5.4. In 5.3 Downsample factor 4 takes off 48.71% vs 50% in 5.4
EDIT: The following images have no reflections enabled. In 5.4 Lumen Probe Gather doesn’t give as much specular compared to 5.3(in 5.3, Lumen reflections appear pink in the same area on the blue cube thing with just probe gather) but, this does make it more like pathtracing
Interesting things. Just to point: I think you are already using the release candidate of the 5.4, as the branch is closed since 4 days ago, so I think this will be the Preview release for the Launcher.
